I would like to register different Providers on different sub-resources but when I try it, it is not working (I get an exception regarding missing provider when the method on the sub-resource was called).

Is it expected? I can't find any information neither in the MP specification nor Resteasy documentation.

Resource proxy

@Path("/foo")
@RegisterProvider(XYZWriter.class)
@RegisterProvider(XYZReader.class)
public interface Foo {
    @POST
    @Consumes("xyz")
    @Produces("xyz")
    FooResponse get(FooContent content);

    @Path("/bar")
    Bar getBar();
}

 Sub resource proxy

@RegisterProvider(ABCReader.class)
public interface Bar {
    @GET
    @Produces("abc")
    BarResponse get();
}

The call

foo.getBar().get();

Only registrations on the resource proxy are done.